"add more" button broken with multiple mediafields and when the user has different language from the site

Difficult to describe in the tiltle.

Problem:
Node saves each time i click on add more on an unlimited value media field.

Setup:
A content type with TWO media fields.
Site is multilingual where domain decides which language is set.

Steps to "possibly" reproduce the problem:
Try to post with user language different than site language.
Add multiple images to one media field,
Add one image to the second.
Click "add more" on the second.

The node gets saved in the background, and no second upload field appears.
Furthermore the add more button description on the second media field changes language